Extractors, as discussed hereinafter, have been used in industry for many years. They are particularly applicable for use in processing agricultural products. Granular or flake material is treated with a solvent so that some amount of a component impregnating the granular or flake material may be dissolved by the solvent in solution and separated. An example of a product an extractor is utilized to process is soybean flakes. Such flakes are typically treated with a solvent such as hexane. The solvent dissolves and separates oil in the flakes.
Another example of a product processed by an extractor is soy protein concentrate. De-fatted soybean flakes are washed with alcohol so as to dissolve and separate carbohydrates in the flakes. A product of this process is carbohydrates. A material with a high concentration of protein is, thereby, produced.
In extractors known in the prior art, the granular or flake material being processed is transported from an inlet of the extractor to an outlet thereof. Transportation is provided by structures such as a drag conveyor. While solvent is poured over a bed of the material, the material is transported from the inlet to the outlet. The efficiency of the extractor is a measure of the rate at which the solvent is able to effectively remove the targeted component from the material.
The bed of material being conveyed is essentially a porous medium. Consequently, as solvent is repeatedly poured onto the top of the bed, it will wash through the bed, make contact with the material and drain out through the screen which supports the material. In an application previously discussed, the hexane wash drains through a slurry of oil-impregnated material. The oil is, thereby, removed from the soybean material.
The geometry of the material bed is not, however, uniform. At various locations within the bed, variation in efficiency will be realized. Some locations within the bed are more open, and some locations are more packed. This can be true for various types of granular or flake material. Consequently, in zones that are more open, there will be a greater flow of solvent than in other locations. In locations where there is less solvent flow, greater extraction time will be necessary.
It is to these dictates and shortcomings of the prior art that the present invention is directed. It is a novel extractor construction that functions to solve problems of the prior art.